RSS Distribution of the Trochocopus subgenus with a new range extension for the neopercul

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    8 May 2007
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    The largely puerile and often intimidating Bodianus is a large genus of labrids most noted for their belligerent and mischevious behaviour. While a large portion of the genus are often teeth bearing invertebrate hunters, a handful are minimally problematic and prove to be ideal and very worthy candidates for the home aquarium. The subgenus Trochocopus features rather small cylindrical members with peppermint stripe motifs and a large pre-opercular earspot as a recurring feature. In this article we explore the various species within this subgenus as well as a range extension for the neopercularis complex.

    [​IMG]Bodianus opercularis, Indian Ocean in distribution.

    Trochocopus features eight members, all of which are moderately deep to very deep dwelling in nature. Due to their penchant for deeper waters, it is undeniably certain that this group is open to future additions. Much of their actual distribution is also lacking, with the difficulty and restrictions that come with deep water exploration.

    Like many other examples in this genus, a few allopatric sisters and species complex are blatantly present here. Bodianus opercularis and B. neopercularis are the model representatives for allopatricity in this group, and are also members of a distinct species complex.

    [​IMG]Bodianus neopercularis. Pacific Ocean in distribution.

    In the beautiful Bodianus neopercularis, the fish is cylindrical with a series of parallel red and white stripes giving this species the iconic peppermint design. The dorsal fin is red and the caudal is flagged in red and white just at the base. A prominent black ear spot sits behind the operculum.

    This species is the first of a series of highly similar members, with one being nearly indistinguishable. B. neopercularis is strictly Pacific in distribution, being found mainly in the Western Pacific waters of Japan, Marshall Islands and Palau. It is highly possible that it ranges further than what is currently documented.

    [​IMG]Bodianus opercularis. Photo by BlueHarbor.

    Bodianus opercularis is nearly identical to the preceding species, and is coloured in the exact same configuration. The main distinguishing morphological feature is the presence of a thicker white rim on the edge of the anal fin in this species, versus a thinner more translucent one in B. neopercularis. Another photo of B. opercularis can be seen two photos up, and the anal fin pattern is quite distinctive.

    The two species are allopatric in distribution, with B. opercularis being strictly confined to the Indian Ocean. Here it enjoys a wide range from Mauritius, parts of Africa, the Red Sea and eastwards to the Christmas Islands. Due to the great similarity in appearance, it is quite likely that the two only started diverging recently when ancestral populations were split up into two separate oceans.

    [​IMG]A pair of Bodianus sepiacaudus. Photo taken at the Henry Doorly Zoo, Omaha.

    Things start to get a little more complicated from here on, and although still in the same species complex, Bodianus sepiacaudus is readily differentiated from the previous two based on the following keys. The usual peppermint motif is present, but in B. sepiacaudus, the red is usually heavily shaded in black, giving the appearance of a more maroon fish. The caudal peduncle region is heavily spotted with a dark brownish red patch, which gives rise to its latin name “sepiacaudus“. A broad white mid-lateral stripe separates the red portion of the tail from this patch.

    B. sepiacaudus is found mainly in Indonesia, inhabiting many islands including Bali, Sulawesi and Flores. In extends northwards into the Philippines as well. The juveniles for this species bear the same striped pattern as the adult, but curiously enough are jet black in place of the usual red. This black juvenile characteristic is shared with two other species, one of which is Bodianus masudai.

    [​IMG]Bodianus masudai. Adult, and juvenile in subset.

    B. masudai is a gorgeous species with the same peppermint motif as usual, but has the white replaced with striking chrome yellow instead. In this species the differentiation away from the standard “neopercularis” type can be seen not only in the coloration, but also in its adult form. B. masudai is significantly larger, with a higher body profile in adult specimens. Although all members in this group are deep swelling, B. masudai can be found in decidedly deeper depths, often beyond 300ft.

    Like B. sepiacaudus, it has also a dusky coloured juvenile. They quickly lose it with age, but it is only in larger adults do the brilliant cherry red really start filling in. B. masudai exudes brilliance when seen in person. It ranges predominantly in the Japanese archipelago, being found in Izu, Oshiwa, Okinawa and various other nearby islands. It can also be found in Taiwan and the Coral Sea, where specimens may represent a distinct form.

    [​IMG]Bodianus izuensis. Adult and juvenile in subset.

    The neopercularis complex ends with B. masudai, and in the next couple of species, the deviation from the standard peppermint form becomes highly apparent. Bodianus izuensis is a peculiar member with rather unusual markings. In this pretty species, it bears a salmon pink ground colour that is more evident in the head, dorsum and caudal region of the body. The central portion of the body is lighter in hue, sometimes white, and is traversed by the usual parallel stripes. The stripes of B. izuensis are black, or blood red, and often pixillated. The lowermost stripe is variable amongst specimens and may or may not be present, and when absent is usually replaced by a pinkish or orange marring.

    The juveniles are unusually shaped, being more pointed in the snout and assumes a less standard design for the Trochocopus subgenus. It is strongly marked in black and white as juveniles, but the black bands distort and fade with age to assume the typical izuensis design. B. izuensis ranges from Indonesia to Japan and far east into Australia and the Coral Sea.

    [​IMG]Bodianus bimaculatus. Photo by Izuzuki.

    B. bimaculatus is the smallest member in this group, and is uniformly orange-yellow. Males may develop a more salmon hue on the central portion of the body. This species lacks any distinct stripes in contrast, but instead possesses weak streaky lines across the body. The usual black “earspot” is present.

    B. bimaculatus is very wide ranging, being found in many areas of the Indo-West Pacific including Palau, Indonesia, Japan, Australia and even Africa. Superficially, B. bimaculatus shares the same colour scheme as the last two members, but the vast greatness in size is a curious artefact for this species.

    [​IMG]Bodianus tanyokidus. Photo from Zukan.

    The exceedingly rare Bodianus tanyokidus is only known from dead specimens mostly obtained from commercial fishing trawlers. This deepwater member shares the same basic coloration as the preceding species, but grows to more than twice the maximum length. Not much is known about this elusive hog, but based on fishing records it appears to have a large geographical distribution.

    In the Indian Ocean it is known from Mauritius and the Comoros. On the Pacific side, B. tanyokidus is found in Japan and the Marianas. It is very likely that the undocumented range is far larger than these locales.

    [​IMG]The Hawaiian endemic Bodianus sanguineus.

    Hawaii contains an endemic form of this group, and it is here in the deep rocky reefs that you can find the brilliant Bodianus sanguineus. B. sanguineus is a luscious persimmon orange with neon yellow highlights on the cheek, tail and the entire length of its dorsum. It possesses the usual cheek spot, and has an additional one on the caudal peduncle. Apart from these features it remains mostly unmarked.

    The endemism in Hawaii has led rise to many unique and unmistakable species, this Bodianus being one of them. This isolated species is not sympatric with any of the other members, and likewise is most distinctive in its coloration. B. sanguineus comes in two colour forms, the usual yellow and orange as well as a white form. The white form will revert to yellow in captivity.

    [​IMG]Bodianus sp “kimura”. Photo by BlueHarbor. The two fishes here are the same specimens, showing colour change of both forms.

    A final potentially new and undescribed Bodianus lurks in the waters of the Southern Pacific. This species is tentatively dubbed B. sp “kimura” after deep diver Rufus Kimura, and most closely resembles Bodianus neopercularis. However a few key differences in coloration serves to separate the two. It is without a doubt a member of the neopercularis complex, but whether or not it turns out to be a distinct species is still subject of future studies.

    [​IMG]A juvenile Bodianus sp. “kimura”, showing the white form. Notice the missing lowermost stripe. This juvenile is the same specimen as the red/white form pictured above.

    Bodianus sp. “kimura” has the usual peppermint design with three horizontal red stripes, but in this species the bottommost stripe is often either completely missing or highly vestigial. It also lacks completely the lowermost cheek stripe. What’s most interesting however is the occurrence of two colour forms. Like B. sanguineus, this unknown species occurs in both a red/white form as well as a red/yellow form.

    [​IMG]Bodianus sp “kimura”, a red/yellow phased juvenile.

    The colour forms are interchangeable, and occur in both adults and juveniles. A juvenile red/white specimen may grow into a red/yellow form, and likewise a yellow phased juvenile may grow up into a red/white individual. The oblique photo above showing the comparison between both colour forms are of the same fish, and are the adult forms of the same red/white juvenile pictured just below it.

    Directly above is a red/yellow phased juvenile of the same species.

    [​IMG]A sub-adult Bodianus sp. “kimura” in its red/yellow phase.

    Rufus Kimura observed both colour forms of this species in the wild, and when collected, both were able to change their colours in reverse orders when maintained in captivity. Why or how this phenomenon occurs, no one really knows for sure. What is consistent though regardless of the coloration, is the transient and very weak lower most stripe in this species.

    [​IMG]A potential Bodianus sp. “kimura”? Photo by Cairns Marine.

    A few days ago Cairns Marine obtained a unique Bodianus from the Coral Sea looking superficially like Bodianus neopercularis. On closer inspection, this specimen lacks the lowermost cheek stripe, and on the body it is only very weakly expressed and vestigial.

    The characteristics and appearance are identical to those of the undescribed “kimura” variants, but whether or not this will eventually change coloration to the yellow form is still anyone’s guess.

    [​IMG]Another look at the Coral Sea Bodianus, with very obvious lack of the lowermost stripe. Photo by Cairns Marine.

    If this is indeed the same fish as the Southern Pacific “kimura” hogfish, then its appearance in the Coral Sea is very perplexing. Exactly how wide is the geographical range? If it is found in-between the Coral Sea and the Southern Pacific, then the likelihood of it being sympatric with Bodianus neopercularis is almost certain.

    It’s unusual to see such divergence between two sympatric species, and although B. neopercularis can sometimes be found in very light orange, it does not have a strongly contrasting yellow morph, and neither can it switch between the two.

    [​IMG]A page from Marine Aquarist no. 70 edition showing the same red/white Bodianus as it grows into a yellow Bodianus “kimura”.

    It will be interesting to follow the development on the Coral Sea Bodianus. Based on its coloration, it appears to be the same species as the “kimura” variants and if so, then potential colour change in aquarium is to be expected.

    In summary, the Trochocopus subgenus is home to eight described members, with one potentially new species from the Southern Pacific and now the Coral Sea. B. neopercularis and B. opercularis are allopatric sisters, and play host to a complex involving B. sepiacaudus and B. masudai.

    Bodianus izuensis diverges away slightly from the others with its strongly pixillated stripes, while B. bimaculatus, B. tanyokidus and B. sanguineus lack the stripes all together. The last unknown member bears resemblance to B. neopercularis, but the lower most red stripe may be highly aberrant or absent.

    Apart from the endemic B. sanguineus, little is known with regards to the actual biogeography of this group and exactly how extensive the sympatry are within the various species. With further deepwater exploration and diving, more information will undoubtedly be revealed.

    As for now, these Bodianus are still shrouded in mystery, much like the habitat in which they dwell.
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